Investigation on the extended range of absorbing film for a microcavity enhanced graphene photodetector

Microcavity is the preferred graphene-based photodetector structure for its perfect feature of narrow spectral width and absorption enhancement, thus its application sheds light on ultra-fast detection in optic telecommunication and sensing fields. Due to an extremely thin film of graphene, the present study naturally deems it essential to locate the graphene in the exact position of resonant peak intensity. Here an extended graphene position margin in asymmetric planar microcavity with absorption higher than 97.35% was demonstrated. The shift of the centre wavelength caused by graphene was revealed to be non-negligible for telecommunication applications and graphene applied devices. The maximum shift beyond the designed wavelength of 1550 nm has reached 1.07 nm in the cavity, which may have severe impact on the DWDM system. Our theoretical investigation amplifies the absorption features and the parasitical spectrum alterations of a designed photodetector with graphene.